Abstract: This study innovatively designs a comprehensive teaching experiment for synthesizing benzofuran-5-carbaldehyde through a tandem strategy involving formylation and conjugated dehydrogenation. Applying the principle of integrating theory with practice, we conducted in-depth mechanistic analysis and systematic optimization of the experimental procedure. Using commercially available 2,3-dihydrobenzofuran as starting material, the target product was successfully obtained via sequential Vilsmeier-Haack formylation and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)-mediated dehydrogenation, achieving an overall yield exceeding 80%. Subsequent low-temperature crystallization enhanced the final product purity to over 95%. This comprehensive experiment features operational simplicity, cost-effective materials, controllable duration, and minimal safety risks, meeting the “High-level, Innovative and Challenging” requirements for undergraduate laboratory education while effectively cultivating students’ innovative thinking and research skills.

Key words: Benzofuran-5-formaldehyde, Formylation, Conjugated dehydrogenation, Tandem strategy, Comprehensive teaching experiment